Conventionally, the present applicant has already proposed a power plant in Patent Literature 1. This power plant is for driving drive wheels of a hybrid vehicle, and in an example shown in FIGS. 2 and 3 in Patent Literature 1, it is provided with an engine, a first rotating machine, and a second rotating machine, as motive power sources.
The first rotating machine includes a hollow cylindrical casing, an input shaft and an output shaft which are rotatably supported by the casing, a stator disposed on an inner wall of the casing along a circumferential direction, a first rotor accommodated in the casing, and a second rotor disposed between the first rotor and the stator, and the stator, the first rotor, and the second rotor are arranged concentrically with each other. In the first rotating machine, the input shaft of the first rotating machine is mechanically connected to an output shaft of the engine, the output shaft of the first rotating machine is directly connected to a rotating shaft of the second rotating machine. Further, the first rotor is concentrically fixed to a front end of the output shaft, and first and second permanent magnet rows extend in parallel with each other along a circumferential direction on an outer peripheral surface thereof. The first and second permanent magnet rows are each formed by a plurality of permanent magnets, and these permanent magnets are arranged at equally-spaced intervals such that each two adjacent permanent magnets have polarities different from each other.
Further, the second rotor is concentrically fixed to a front end of the input shaft, and first and second soft magnetic element rows extend in parallel with each other along a circumferential direction on an outer peripheral surface thereof. The first and second soft magnetic element rows are each formed by a plurality of soft magnetic material cores arranged at predetermined intervals along the circumferential direction, and the soft magnetic material cores of the second soft magnetic element row (hereinafter referred to as “the second cores”) are arranged in a manner displaced by an electrical angle of π/2 with respect to the soft magnetic material cores of the first soft magnetic element row (hereinafter referred to as “the first cores”). Further, the stator includes a plurality of armatures arranged at predetermined intervals, and coils of each three adjacent armatures are arranged as three-phase coils that generate a rotating magnetic field while exhibiting a U-phase, a V-phase, and a W-phase, respectively, when electric power is supplied thereto.
In the first rotating machine arranged as above, when electric power is supplied to the stator, a first rotating magnetic field and a second rotating magnetic field are generated in the stator such that they rotate in the circumferential direction of the stator, and in accordance therewith, the first and second cores are magnetized by magnetic poles of the first and second rotating magnetic fields and magnetic poles of the first and second permanent magnets, whereby magnetic lines of force are generated between these elements. Further, the first and second rotors are driven by the generated magnetic lines of force, which causes motive power to be output from the output shaft or the input shaft.
On the other hand, the second rotating machine is formed by a DC brushless motor, and a rotating shaft thereof is mechanically connected to the drive wheels. In the above-described power plant, the respective operating states of the engine, the first rotating machine, and the second rotating machine are controlled according to the operating state of the hybrid vehicle, and as a result, the drive wheels are driven by the motive power generated by these motive power sources.